Known as the land of 10,000 lakes, Minnesota’s many bodies of water form an integral part of the state’s identity year-round. The summertime recreational usage of the state’s actual 14,380 lakes includes swimming, boating and fishing, all of which can be experienced in rural towns and major cities throughout Minnesota.
For many residents and tourists alike, though, the most noteworthy season in Minnesota is winter. For those brave enough to endure the colder temperatures, there is opportunity to access the recreational activities the state is revered for. These chilly endeavors include ice fishing and skating, snowshoeing and cross country skiing. And don’t assume swimming is just for summer — many Minnesotans frequently opt for a chilly polar plunge at their local lake every winter.
Minnesota’s winter recreation is heavily dependent on ice coverage on the lakes (there’s no ice fishing or ice skating without ice, of course). But climate change is impacting the length of the state’s ice season, and in turn is putting Minnesota’s recreation economy and local ecosystems at risk.
Data released by the Minnesota Pollution Control Agency (MCPA) and Department of Natural Resources (DNR) shows Minnesota’s lake ice season has decreased by up to three weeks over the past 50 years. In that time, the state has lost 10 to 14 days of lake ice on average.
Comparatively, winter hits this northern state sooner and leaves later than the rest of the United States. This allows for the lakes to have a thick frozen layer of ice for a longer period of time in the winter. Consequently, ice-based recreation has historically thrived here, and Minnesota is home to the largest ice angler — or fisherman — population in the nation.
The duration of the lake ice season is determined by ice-in and ice-out dates. Ice-in dates occur when the entire lake is frozen over and the ice cover remains through winter. Ice-out dates are calculated as the first day a lake is completely ice free, when it is possible to navigate from point A to point B without encountering ice, or when a lake is 90 percent free of ice. Twin Cities area lakes’ median ice-in dates range from late November for smaller lakes to around December 11 for bigger lakes. The median ice-out date ranges from March 18 for smaller lakes to after May 12 for bigger lakes.
Some of the more frequently visited lakes have lost up to almost three weeks of ice.
Minnesota is not alone in experiencing shorter ice seasons.
“It's not just in Minnesota,” Peter Boulay, climatologist for Minnesota’s DNR, said. “Some of these records are in Madison, Wisconsin, where they have over 150 years of lake and ice data now, and they are seeing the same kind of pattern.”
This pattern, witnessed and documented all around the Midwest, includes a general warming of temperatures.
“In the Twin Cities, we used to get to minus 20 degrees in the winter. Someplace like St. Cloud, they used to get down minus 30 degrees pretty regularly in the winter. It's hard to do that these days. We've kind of cut the edge off the extreme cold in winter, and that's reflected in what's going on in the lakes,” Boulay said.
These changes have severe ramifications for outdoor recreationalists and business owners. Warmer lakes and shorter winters impact industries that rely on the millions of dollars spent on winter recreation in Minnesota.
For example, a major cultural and economic component to Minnesota’s winters includes ice fishing. The dozens of yearly tournaments draw participants and tourism dollars to local communities. However, in examining the relationship between temperature and ice fishing tournaments, researchers from the University of Minnesota found a higher number of tournament cancellations in the central part of the state when average winter air temperatures reached 24.8 degrees Fahrenheit or warmer.
“As it applies to my career and recreation education, I've seen a lot more backup plans being needed,” Nick Sacco, outdoor recreation program specialist for Three Rivers Park District, said. “However, some activities don't have backups, and we just have to cancel. In a perfect world, I'd love to be doing more ice fishing in March like my dad did when he was young. People used to do it with confidence, but it’s becoming less of [a] reality in Minnesota because we're finding less ice.”
The shortening ice season also shapes the fish diversity, impacting agencies like the fisheries of Minnesota.
“I think some of the more common changes that we see is that a lot of our warm water species, like our bluegill and our largemouth bass, are more abundant than they used to be. And some of our coldwater species have declined over time. And these events, kind of gradual changes, go back to about the 1970s,” David Weiztel, DNR fisheries supervisor for the Grand Rapids area, said.
Due to the shortening ice seasons, these fisheries have seen an increase in bass fishing, a warm water fish, as opposed to a coldwater fish, such as walleye. This results in the decline of entire species of fish, damaging the diversity of underwater ecosystems.
“Coldwater fish have to deal with a shortened season and higher water temperatures in the summer, so we're seeing more frequent summer kills,” Weiztel said. “Those extra two weeks can make a big difference in how big [fish] are, come late fall, and how well [they] survived that first winter.”
According to Weiztel, this change has most heavily impacted the anglers.
“Some of the stuff that people may have traditionally enjoyed are a little bit harder to catch, or maybe they're in fewer lakes,” he said. “I've been working in Grand Rapids for about 15 years. When I started here, most of the phone calls that I got were from walleye anglers. Well, now there's a ton of interest in bass fishing,” Weiztel said.
The changing climate plays a significant role in impacts to the fishing industry, but agencies are doing their best to adapt.
“It's hard to mitigate actually, especially the climate stuff. So, kind of what we've done here in Minnesota is taking a look at where our cold water resources are located and tried to protect the watersheds that surround them. This is because they're going to be very susceptible to change in the long run,” Weiztel said.
There is a statewide effort to monitor and mitigate the changes the climate has on the ice season, but the work is far from complete. Out of the 14,380 lakes in Minnesota, only about 700-800 are monitored annually as part of a multi-agency effort between the Minnesota DNR, State Climatology Office and the Minnesota Pollution Control agency. Some more remote areas are hard to access, and much of the data collection work relies almost completely on citizen volunteers.
These unpaid volunteers include anyone living near a lake, recreationalists, business owners, environmentalists, and more. To volunteer, all that is required is to post the ice-in or ice-out date, lake name and county to the Minnesota DNR Climate Office Facebook page. The DNR’s dependence on citizen volunteers provides an opportunity for those impacted most by the shrinking ice season to document these changes publicly.
Boulay of the DNR says their help in monitoring lakes is invaluable to the continuation of this data collection.
“Citizen scientists, or volunteers, are out there watching the lakes, and we wouldn't be able to do this without them. We wouldn't have the data. I've talked to many, many people over the years, and they are very dedicated to their lake. You know, we love our lakes, and we like to watch them,” he said.